JP2001060558A - Inert barrier for high-cleanliness epitaxial deposition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life of main chamber O-rings and prevent the infiltration of O-ring contaminants into a treating region by arranging vacuum tight seals and nonreactive barriers between upper and lower members forming the treating region. SOLUTION: In an epitaxial silicon chemical vapor deposition cycle or cleaning cycle, a depositing gas or heating cleaning gas is introduced to a treating region 18 from an external source via a supply line 30. Since the region 18 is formed in upper and lower domes 12 and 16 and hermetically sealed with O-rings 52, 54, 56, 58 and 60, barriers 64 and 66, having heat resistances and chemical resistances, prevent the heated depositing reaction product or the heating cleaning gas, which advances into the gap between a liner 118 and the domes 12 and 16 from reaching the O-rings 56 and 58 during the deposition or cleaning cycle. In addition, the barriers 64 and 66 made of the same material prevent the possibility of contaminants or particles produced from the O-rings 50, 52, and 60 reaching the treating region 18 and coating the region 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor processing apparatus, and more particularly, to insulating an O-ring by using an inert barrier to prevent O-ring contamination in a processing area.

[0002]

2. Description of the Related Art Today's semiconductor industry equipment seeks to achieve high throughput by transitioning from a 200 mm substrate to a larger diameter, eg, 300 mm. Larger substrate diameters necessitate higher gas flow rates and higher energy inputs to enable the same process results to be achieved with smaller diameter substrates. At the same time, higher deposition cycles require higher throughput. However, as the number of deposition cycles increases, the number of cleaning cycles increases in direct proportion, especially in those areas of processing that utilize periodic cleaning cycles. One example of a process that utilizes periodic cleaning is the deposition of epitaxial silicon. In an epitaxial silicon reactor, a typical cleaning cycle is particularly difficult because
This is because there is a step of heating the processing region to about 1200 ° C. and injecting HCl. The combination of the large energy demands of large substrates and the desire for long cleaning cycles has put strain on existing reactor designs. Exposed components, such as the innermost O-rings and those closest to the process area, are particularly vulnerable to the great demands described above. In a typical reactor, these O-rings provide a pressure seal for the processing chamber and are exposed to the heat and chemical reactions of the deposition and cleaning cycle.

FIG. 1 is a representative example of a double dome processing reactor suitable for chemical vapor deposition (CVD) of silicon films, such as an EPI chamber available from Applied Materials, Inc. of Santa Clara, California, USA. In this figure, the CVD reactor 10 has a top dome 12, a bottom dome 16, and side walls 14, 15, which are
Together, they define a processing area 18 into which a single or multiple substrates, such as silicon wafers 20, can be loaded. The wafer 20 is placed on a susceptor 22 that can be rotated by a drive 23 to provide a time-averaging environment for the cylindrically symmetric wafer 20. Quartz ring 1
18 is located between the side walls 14 and 15 and the susceptor 22. A preheating ring 24 is supported by the quartz ring 118 and surrounds the susceptor 22.

[0004] Wafer 20, preheating ring 24 and susceptor 2
2 is a plurality of lamps 2 provided outside the processing area 18.
Heated by 6. Top dome 12, bottom dome 16
And insert 118 are typically made of quartz, because they are transparent to both visible and IR frequencies of light and also exhibit relatively high strength. And is chemically stable within the processing environment of the chamber. Side walls 14 and 15 have clamping rings 40 and 42 used to secure top dome 12 and bottom dome 16 to base ring 44. Clamp rings 40 and 42 and base ring 4
4 is typically made of stainless steel.

The structure of the side walls 14 and 15 and their relationship to the processing area 18 can be better understood with reference to FIG. FIG. 2 illustrates an enlarged view of the side walls 14, 15 and the insert 118. O-ring 50,
52, 54 and 56 are used to form a seal between the upper clamp ring 40 and the base ring 44 to allow a pressure seal between the top dome 12 and the processing area 18. Further, O-rings 50, 52, 54 and 5
6 is configured to structurally support the top dome 12 and counteract loads and thermal stresses. The substantially vertical alignment between the O-rings 50 and 54 and between the O-rings 52 and 56 indicates that the top dome 12 is in compression with only a slight cantilever load. Top dome 12 is not in contact with upper clamp ring 40 or base ring 44. Thus, there is a gap between the top dome 12, the upper clamp ring 40 and the base ring 44.

[0006] The lower dome 16 is similarly supported.
O-rings 58 and 60 are used to form a seal between the lower clamp ring 42, base ring 44 and bottom dome 16. Like the top dome 12, the bottom dome 16 is not in contact with the side wall elements that support it. There is a gap between the bottom dome 16 and the rings 42 and 44. Also, there is a gap between the quartz insert 118, the top dome 12, and the bottom dome 16.

Referring to FIG. 1, process gas (whether reactant or dopant or cleaning) is supplied from an external source to the process area 18, which is represented schematically by two tanks 28. Gas is supplied from gas supply 28 along gas supply line 30 to gas inlet 3.
2 and flows into the processing area 18. From the port 32, gas flows through the flow paths of the side walls 14 and 15 and the flow path of the quartz insert 118. From insert 118,
The gas flows in the direction of arrow 34 between susceptor 22 and wafer 20.
, Flows across the preheat ring 24 and is exhausted from the region 18 via an exhaust port 36. A pumping source or other exhaust piping system is coupled to the exhaust port 36 for exhausting gases and by-products from the processing area 18. Although the thermal gradient due to the rotation of the wafer 20 and the heat from the lamps 26 has a small effect on the flow profile, the dominant form of the gas flow profile is from the gas input port 32 and from the preheating ring 24 Wafer 2
This is a laminar flow that crosses zero and reaches the exhaust port 36.

[0008] The above-described CVD processing chamber can accommodate a number of different processes. Each process differs according to the desired end result and has separate considerations in this regard. In a polysilicon deposition process, typically a dope process or an undoped silicon layer
It is deposited on the wafer using a process such as low pressure chemical vapor deposition (CVD). In this process, a reactant gas mixture containing a silicon source (such as silane, disilane, dichlorosilane, trichlorosilane, and silicon tetrachloride) and an optional dopant gas (such as phosphine, arsine, and diborane)
Is heated, the wafer also passes over, and a silicon film is deposited on its surface. In some embodiments, a non-reactive carrier gas, such as hydrogen, is injected into the processing chamber along with one or both of the reactive gas and the dopant gas. In this process, the crystallographic properties of the deposited silicon depend on the deposition temperature. Silicon deposited at a low reaction temperature of about 600 ° C. is largely amorphous, and using a higher deposition temperature of about 650 ° C. to 800 ° C.,
A mixture of amorphous silicon and polysilicon or only polysilicon is deposited.

After each deposition sequence, or after a series of deposition sequences, the processing region 18 may be cleaned. In a typical HCl-based periodic cleaning cycle, a chamber cleaning cycle is performed each time 10-20 μm of silicon is deposited in the reactor 10. The cleaning cycle is performed after removing the last wafer of the sequence from the chamber 10. With no wafer present in the chamber, the susceptor temperature is increased to about 1200 ° C. while providing a mixture of HCl and H 2 to the processing area 18. HCl decomposes the silicon deposits formed in processing area 18 into volatile by-products,
This is exhausted from the processing area 18 via the exhaust port 36.

[0010]

One of the problems with current CVD reactors is that the O-rings 50, 52, 54, 5
6, 58 and 60 may be degraded by prolonged exposure to the chemicals, temperatures and pressures used in processing area 18 during the deposition and cleaning processes. A typical removal rate for the above HCl cleaning process is about 2 μm / min. If a long deposition sequence is performed, for example, a deposition of about 20 μm is performed between cleanings, a high throughput can be obtained.
Increase the length of exposure to HCl at 1200 ° C., increasing the likelihood of O-ring degradation failure. If the O-ring is deteriorated or cut, loss of process environment control such as loss of pressure control is caused, and the processing region 18 is contaminated and a film is formed thereon.

One indication of the lack of contamination or cleanliness level in the processing region 18 is to measure the resistivity of a non-doped epitaxial silicon film deposited in the region 18. Silicon has a high resistivity in the intrinsic of the order of 800Ω-cm or more, so if the measured specific resistivity is 800Ω-cm or less,
This indicates that the inside of the processing area is slightly contaminated. First, a high degree of cleanliness in the region 18 is desired so that the dopant is more likely to be included to provide a doped silicon film having a specific resistivity. O-rings, such as those utilized as in FIGS. 1 and 2, typically have a deposition cycle of about 20 μm or 1200 ° C., HC
l is limited to cleaning cycles of less than about 30 minutes. Because of the direct exposure to region 18, any deterioration or breakage of these O-rings (56 and 58) will lead to contamination of the processing region, thereby increasing the resistivity to 20-30.
It is on the order of Ω-cm.

The O-ring seal type reactor has a throughput capability of 20 μm between cleanings.
There is a need for processing equipment that can overcome the shortcomings of the prior art by being larger. Such a reactor would allow for a long high temperature epitaxial deposition cycle, such that films of about 20 μm or more could be deposited. This reactor will extend the duration of HCl cleaning while also preventing O-ring based contamination from reaching the processing area.

[0013]

One aspect of the present invention is an improved semiconductor substrate processing apparatus that includes a processing chamber having a first member, a second member, and a processing region. A vacuum tight seal between the first member and the second member to enable a pressure controlled environment within the processing region; and a first member and a second member separating the seal from the processing region. A barrier disposed between the two members and substantially non-reactive to processes performed in the processing region.

[0014] Another aspect of the invention is an improved apparatus for depositing silicon, the apparatus comprising: a processing chamber having a first element, a second element, and a processing area; An O-ring between the first and second elements to enable a pressure controlled process in the processing area;
An expanded tetrafluoroethylene resin that is substantially inert to temperature, pressure and chemical environment within the processing region; a linear shaped material comprising the material;
And a second notched end adapted to be mated with the first notched end, a thickness and a length, wherein the linear material comprises the first notch. When the scored end is joined to the second notched end, it circumscribes the processing area, whereby the inert material
Separate the processing area from the O-ring.

[0015] Another aspect of the invention is an improved apparatus for depositing silicon, the apparatus comprising a processing chamber, a seal, and a barrier, the processing chamber comprising a top dome, a bottom dome, and a bottom dome. A dome, and a clamp ring coupled to the base ring to separate the top dome and the bottom dome, wherein the top dome, the bottom dome, the base ring, and the clamp ring define a processing area; A susceptor arranged in the processing area;
A plurality of lamps illuminating the susceptor, and a quartz liner arranged adjacent to the susceptor,
The seal includes a seal disposed between the base ring and each of the domes, and a seal between the clamp ring and each of the domes.
The base ring and the clamp ring contact the seal to provide a pressure controlled environment within the processing region in a compressible state, wherein the barrier is disposed between each of the seals and the processing region; The barrier prevents contaminants from the seal from reaching the processing area;
The seal and the barrier are disposed in a groove formed in the clamp ring and the base ring.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the use of an inert barrier material to extend the life of a primary chamber O-ring and prevent O-ring contaminants from reaching the processing area of a semiconductor processing reactor.

Specific details of the invention are set forth in accordance with the invention.
This can be better understood with reference to FIG. 3, which is a cross-sectional view of the side wall of the processing reactor 15 having the inert barriers 62, 64, 66 and 68. Process reactor 15 is a double dome CVD reactor similar to prior art process reactor 10, thus common components are referenced by the same reference numerals.

The top dome 12 has O-rings 50, 52,
It is held in place by the compressive forces acting on 54 and 56. The O-ring is disposed in a groove formed on each surface of the upper clamp ring 40, the lower clamp ring 42, and the base ring 44. O-rings are made of materials that are most compatible with semiconductor processes and various load situations. A typical O-ring material is silicone and also Teflon®, Viton, Kalrez
And various fluoro compounds such as various O-ring compositions wrapped in Teflon. Top dome 12 is not in contact with upper clamp ring 40 or base ring 44.

The top dome 12 has a quartz ring 118
But does not form a seal. An inert barrier 62 is located adjacent to the O-ring 52, and an inert barrier 64 is located adjacent to the O-ring 56. The inert barriers 62 and 64 are installed in the process area 1 during installation.
Circumscribe 8; Since there is no seal between the quartz insert 118 and the top dome 12, the inert barrier 64
Are exposed to process gases and chemicals in the process area 18. However, because the barrier 64 stands between the top dome 12 and the base ring 44, the O-ring 56
Not exposed to process chemistry present within. Furthermore, O
Any contaminants released by the ring 56 cannot pass through the barrier 64 and therefore the processing area 18
Is prevented from being contaminated. Particularly with respect to the O-ring 56, the barrier material 64 is disposed adjacent to the O-ring 56, circumscribes the processing region 18, and is between the process region 18 and the O-ring 56.

The bottom dome 16 is connected to the lower clamp ring 4.
It is held in place by the compressive force acting on the O-rings 58 and 60 by the base ring 44 and the base ring 44. The lower dome 16 is connected to the lower clamp ring 42 or the base ring 4.
No contact with 4. Although the quartz ring 118 contacts the lower dome, it does not form a sealing surface with the lower dome 16. Inert barrier 66 is located adjacent to O-ring 58, and inert barrier 68 is located adjacent to O-ring 60. Inactive barriers 66 and 68 circumscribe process area 18 during installation. Because there is no seal between the quartz insert 118 and the bottom dome 16, the inert barrier 66 is exposed to process gases and chemicals in the process area 18. However, O-ring 58 is not exposed to process chemicals present in region 18 because barrier 66 stands between bottom dome 16 and base ring 44. Further, it prevents any contaminants emitted by the O-ring 58 from passing through the barrier 64 and thus contaminating the processing area 18. Especially O-ring 58
The barrier material 66 is disposed adjacent to the O-ring 58 and circumscribes the processing region 18 and
It is between the rings 58.

O-rings 56 and 58 form a primary vacuum tight seal between chamber members adjacent each O-ring. The O-ring 56 is connected to the upper dome 12 and the base ring 4.
The O-ring 58 forms a seal between the lower dome 16 and the base ring 44 while forming a seal between the four.
The seal formed by the O-rings 56 and 58 allows vacuum, atmospheric and high pressure operations to be performed within the processing area 18. For epitaxial silicon deposition, the process pressure can take anywhere from about 10 Torr to 1000 Torr. Typical pressures are 760 Torr for atmospheric processes and about 20-100 Torr for reduced pressure processes.

Using the O-rings 50, 52, 54 and 60, the compressive force and the load force of the clamp ring and the base ring are uniformly distributed over the entire surface of the upper dome 12 and the lower dome 16. O-rings 50, 52, 54 and 60 also act as secondary pressure seals for processing area 18.
Thus, all sealing and loading forces are supported by O-rings 50,52,54,56,58 and 60. Also, separate grooves formed in the upper clamp ring 40, the lower clamp ring 42 and the base ring 44 to accommodate the O-ring and barrier material of the present invention are provided in a typical double dome reactor of the present invention. This is exemplified in a specific example. The base ring 44 includes separate supporting and sealing O-rings, such as a groove 70 that accommodates the primary sealing O-ring 56 and barrier 64 while the groove 72 accommodates the support and the secondary sealing O-ring 54. provide. The base ring 44 also provides a combined seal and support O-ring, as can be found in the groove 78 that accommodates the support and secondary seal O-ring 58 and barrier 66. Groove 76, main seal O-ring 52 and barrier 6 to accommodate support and seal O-ring 50
2 with a separate support and seal O-ring design with a groove 74 to accommodate
Is exemplified. Seal and support O-ring 60 and barrier 6
8 illustrates a seal and support coupling O-ring with a single groove 80 to accommodate the lower clamp ring 42. The arrangement of the O-ring and barrier and the configuration of the groove illustrated in the specific example of FIG. 3 are merely representative of the O-ring, barrier arrangement and groove configuration design. Those skilled in the art will appreciate a wide variety of this O-ring and barrier arrangements, and groove-sized designs can be used without departing from the essence of the invention. These alternative designs and configurations will vary depending on the size and type of reactor in which the barrier of the present invention is used.

Inert barriers 62, 64, 66 and 68
Is under compression, but is not considered as a load, distribution or support portion for the upper dome 12 and the lower dome 16. In addition, the provision of a pressure seal for the processing area 18 provides for inert barriers 62,6.
4, 66 and 68 are not relied upon. In fact, tests performed in a processing reactor similar to reactor 15 using barriers 62, 64, 66 and 68 alone (i.e., without O-rings) were sufficient to maintain proper pressure control within processing area 18. Could not provide a good seal. Since the inert barrier materials 62, 64, 66 and 68 alone are unsuitable for sealed semiconductor processing reactors, the processing area 18
Pressure seal is provided by a seal and support O-ring disposed between the upper dome 12 and the lower dome 16 under the compressive forces of the clamp rings 40 and 42 and the base ring 44.

Inert barriers 62, 64, 66 and 68
Insulates the O-ring from convective heat generated in the processing region 18. One reason for placing the barrier between the processing region 18 and the O-ring is that the hot gas from the processing region 18 will only contact the barrier and not the adjacent O-ring. The O-ring not only conducts heat from the stainless steel components of the side wall 14, but also the dome 1
Significant heat energy is received by the radiation from lamp 28 sent through 2 and 16. Further, because a gap exists between the quartz domes 12 and 16 and the insert 118, the inert barriers 64 and 66 come into contact with the deposition and cleaning gases used in the processing area 18. O-rings 58, 54 and 56 are provided for the high temperature epitaxial silicon deposition chemistries used during the deposition process because inert barriers 64 and 66 form an effective barrier between base ring 44 and top and bottom domes 12 and 16. No exposure, and more importantly, no exposure to the hot HCl-based chemicals used during the cleaning process.

The materials used for the inert barriers 62, 64, 66 and 68 must be substantially non-reactive or inert to the chemicals, temperature and pressure utilized within the processing area 18. . Such materials have a temperature between 950 ° C and 12 ° C.
Exposure could be continued to a susceptor temperature of 50 ° C. and a reactive source gas typically used during epitaxial silicon deposition. Further, such a material would allow a susceptor temperature of 1200 ° C. and prolonged exposure to HCl-based cleaning chemistries. Such materials will not suffer from degradation or contamination and will withstand prolonged exposure to both epitaxial silicon deposition and cleaning cycles. In the chamber 15 of FIG. 3, typically, when the susceptor temperature is 1200 ° C., the temperature near the barrier materials 62, 64, 66 and 68 is about 28
It becomes 0 degreeC-480 degreeC. Further, the barrier material must be arranged such that O-ring contaminants do not reach the processing area 18 relative to any path between the O-ring and the processing area 18. For example, the barrier 64 is arranged to block the passage from the O-rings 54 and 56 to the gap between the top dome 12 and the quartz insert 118 and the closing to the processing area 18.

A material having excellent heat resistance and chemical resistance suitable for use as a barrier material includes tetrafluoroethylene resin (PTFE). As taught in U.S. Pat. No. 3,953,566 issued Apr. 27, 1976 to Gore, PTFE may be produced in an expanded porous form. Also, together
US Patent 5,495 assigned to WL Gore Associates
As discussed in US Pat. No. 4,301 and US Pat. No. 5,492,336, suitable barrier materials also provide long term creep by covering the elongated or expanded PTFE core with a high strength membrane of expanded PTFE. A restricted version may be generated. One suitable barrier material is expanded tetrafluoroethylene resin having high multi-directional tensile strength, which is available from WL Gore Associates under the trade name GoreBG.

FIG. 4 shows an expanded PT according to an embodiment of the present invention.
The FE barrier material is exemplified. The following illustrative example is described with reference to barrier 64, but with barriers 62, 66 and 6
8 is formed similarly and used in the processing reactor 15 according to the invention. As shown in FIG.
Is cut into a linearly shaped continuous piece having ends A and B adaptively connected to the overall length (l), width (w) and thickness (t). When used in a processing reactor according to the present invention, the PTFE barrier exhibits shrinkage. Thus, the barrier sizes l, w, and t are advantageously selected to compensate for changes in barrier dimensions as a result of processing chamber operation. For example, length
Shrinkage along l is accommodated by ends A and B slidably and adaptively connected.

Adaptably joined ends A and B are notched on both sides, the notched width being about half to 1/2 w of the full width of barrier 64. Width w is 1/2 w Make it wide enough to be an effective barrier. The width 1/2 w is shown in FIG.
Adaptably coupled end as described with respect to
Used with A and B. The thickness t is selected such that sufficient contact remains between the barrier and adjacent elements to form an effective barrier. Under operating conditions of the processing reactor in which the barrier is installed, the sizes l, w and t of the barrier material are selected such that the barrier material provides an effective O-ring barrier.

The length of the barrier 64 in FIG. 4 is at a first temperature or at an ambient temperature of about 85 F to 29.4 ° C., or at ambient conditions in the wafer processing apparatus when the reactor 15 is not operating. , The initial pre-shrink length of the barrier 64. In a preferred embodiment, where reactor 15 is a double dome CVD reactor capable of processing 300 mm substrates, barrier 64 has a square cross section and an initial length of about 64 inches, or a thickness (t) and width (w) of 0.285 each. Having a cross-section that is inches. In the specific example described below, the O-ring 5
6, the following description describes the barriers 62, 66 and 68 and the O-ring 5
Also applicable to 2, 58 and 60.

FIG. 5 illustrates a top view of a representative barrier 64 of the present invention when installed in a reactor 15 under atmospheric conditions. When installed in the reactor 15, the barrier 6
Reference numeral 4 circumscribes the processing area. The inner diameter D is about 2 for a typical processing reactor 15 capable of processing 300 mm substrates.
0.3 inches. FIG. 6 is an AA diagram of FIG. 5, illustrating a rectangular cross-sectional shape of a representative barrier 64. Although a rectangular cross-section is illustrated here, those skilled in the art will recognize that circles, ellipses, polygons, and other suitable other cross-sections may be used without departing from the essence of the invention.

FIG. 7 illustrates an enlarged view B of FIG. At ambient conditions or before the barrier 64 shrinks, the initial length of overlap (Loi) between the adaptively joined ends A and B is:
Co-exists with the length of the notched portions at ends A and B. In other words, in the atmosphere or the state before the contraction, the barrier 64 has the width w over the entire length of the barrier 64 or the entire circumference of the processing region 18.
Only the processing area 18 will be separated from the adjacent O-ring.
In a typical barrier 64, the initial overlap (Loi)
Is about 3 inches, which corresponds to the length of each of the flexibly connected ends A and B.

FIG. 8 illustrates the enlarged view B of FIG. 5 after the barrier 64 has been exposed to the deposition and cleaning operations performed in the processing area 18. As a result of the contraction along the barrier 64, the overlap region illustrated in FIG. 8 has been reduced to the Lof or the final length of the overlap. This gives the overall width w between the processing area 18 and the adjacent O-ring, as the final length of the overlap represents the remaining overlapping portions of the adaptable notched ends A and B. As the adaptively coupled ends A and B move from the initial position shown in FIG. 7 to the representative final position shown in FIG.
Lr or reduced width is created. Thus, LrA
Represents the amount of length reduction associated with the end A that is adaptively connected. Similarly, LrB is the compliantly connected end B
Represents the amount of length reduction associated with LrA and L of barrier 64
The portion associated with rB represents the portion of the barrier 64 where only about half of the initial width of the barrier 64 remains between the processing region 18 and the adjacent O-ring. Thus, the initial width w of the barrier material must be sufficient that a thickness reduced to about half of w still provides adequate barrier material capability. In an exemplary embodiment where chamber 15 is a double 300 mm dome CVD reactor and the initial unshrink length (l) of barrier 64 is about 64 inches, the initial overlap (Loi) is about 64 inches. 3 inches.

After shrinkage has occurred in the barrier material 64, the final length of the overlap (Lof) is about 1.5 inches. Alternatively, the total length of the reduced thickness (Lr), representing the sum of each Lr associated with the compliantly joined ends A and B, is about 1.5 inches. Another desirable quality of the barrier material 64 is that shrinkage along the length occurs preferentially and shrinkage along the thickness and width is minimal to zero. As described above and illustrated in FIGS. 7 and 8, the barrier 64 has a principal axis of shrinkage that is
, So that the total shrinkage along the length of the barrier 64 is compensated by the flexibly joined ends A and B.

The use and placement of an exemplary barrier 64 can be better understood with reference to FIGS. FIG. 9 illustrates the placement of O-rings 54 and 56 and barrier 64 on base ring 44 prior to placement of quartz dome 12 and installation of upper clamp ring 40. Although illustrated with the base ring 44 and the upper dome 12, similar techniques and size requirements apply to the O-rings 50 and 52 of the upper clamp ring 40, the barrier 62, and the base ring 44.
Are applied to the O-ring 58 and barrier 66 on the lower surface of the lower clamp ring 42 and the O-ring 60 and barrier 68 of the lower clamp ring 42, respectively. The barrier 64 includes an O-ring 56 in a groove 70 formed in the stainless base ring 44.
It is arranged adjacent to. When bonding the barrier 64 to the base ring 44 or the O-ring 56, no adhesive is used. More importantly, no adhesive should be used because the adhesive impairs the degrees of freedom employed at the notched, slidably coupled end of the barrier 64. The slidably coupled ends A and B of the barrier 64 are free to move along the circumference of the processing area 18 within the groove 70 to compensate for shrinkage of the barrier 64 along its length,
The intention is to ensure a suitable separation between the adjacent O-ring and the processing area 18. O of other loads and seals
Additional grooves are provided to accommodate rings and barriers. For example, a support and seal O-ring 54 is located in groove 72 and an O-ring 56 is located in groove 70 adjacent to barrier 64. Grooves 72 and 70 are formed in base ring 44.

The groove 70 has the size of the reactor 15,
It has a depth (d) that matches the overall thickness of the base ring 44 and the diameter of the cross-section of the O-rings 54,56. After determining the groove depth, the initial thickness of the barrier or the unloaded thickness t is selected to ensure sufficient contact between the top and bottom barrier surfaces and the member between which the barrier is located. The loading conditions of the barrier material provide sufficient compressive force to ensure that the barrier can separate the O-ring from the processing area. Also, the initial thickness or unloaded thickness t compensates for the barrier shrinkage that occurs in the t direction. The thickness t is selected such that, when shrinkage occurs in the t direction, the barrier material fills the allotted space between the members with sufficient contact to provide an effective barrier. As a result, as far as the barrier material shrinks in the t direction,
The barrier remains intact and separates the adjacent O-ring from the processing area.

In a typical embodiment where the reactor 15 is a CVD double dome reactor capable of processing 300 mm diameter workpieces and the unloaded thickness (t) of the barrier 64 is 0.285 inch, the depth of the groove 70 is The height is about 0.215 inches. A suitable barrier material will have an initial or unloaded thickness on the order of 1.3 to 1.5 times the depth of the groove 70 in which it is installed. Thus, the exemplary embodiment of FIG. 9 illustrates a groove depth of 0.215 inches and an initial barrier thickness of 0.285 inches, where the thickness of the barrier is less than the associated groove depth. This means that it becomes about 1.32 times. O-ring 5
To position the 0, 52, 54, 58 and 60 and barrier materials 62, 66 and 68 similarly, additional grooves are
Formed on top clamp 40, base ring 44 and bottom clamp 42.

In the load condition illustrated in FIG. 10, the upper clamp ring 40 and the base ring 44 provide a compressive force on the O-rings 50, 52, 54 and 56 to support the top dome 12. 10, the spacing 75 is maintained between the stainless steel base ring 44 and the top quartz dome 12. In the exemplary embodiment of FIG. 10, spacing 75 is on the order of 0.02 inches. Similar spacing exists between the upper clamp ring 40 and the top dome 12. Although not shown in FIG. 10, the bottom dome 16 and both base rings 4
There is spacing between 4 and lower clamp ring 42. As a result of the compressive load between the clamp ring 40 and the base ring 44, the upper dome 12
2, 54 and 56. Although not used to enable pressure sealing of the processing region 18, the barriers 62 and 64 are also compressed from their original thickness. For example, FIG.
The zero barrier 64 goes from an initial unloaded thickness of about 0.285 inches to a thickness of about 0.235 inches. this is,
Indicates a small compression force.

Although this force is insufficient for the seal, the top dome 1 through the groove 70 ensures that an effective barrier is formed between the O-ring 56 and the processing area 18.
It is sufficient to ensure complete contact between the base ring 44 and the base ring 44 in the width direction of the barrier 64.

It has been demonstrated that processing chambers using the barrier layers of the present invention have high throughput and improved processing windows. For example, in a prior art system utilizing only O-rings (ie, chamber 10), 2
After three consecutive 0 μm deposition cycles, 1200
There is a limitation that cleaning of HCl is performed once at ℃. Furthermore, the resistivity of epitaxial silicon produced in prior art reactors after performing the above deposition and cleaning sequences is on the order of 20-30 ohm-cm.
Typically, intrinsic silicon resistivity below 200 ohm-cm is unacceptable for most commercial epitaxial silicon operating conditions. The low resistivity in this case is O
It indicates ring degradation and possible damage or other contamination in the processing area 18.

Turning to FIGS. 11, 12 and 13, the insulating and contaminant preventing properties of a processing reactor utilizing the barrier layer of the present invention can be better understood. FIG.
Illustrates a stress test performed in reactor 15 to evaluate the improved insulating properties of the barrier material of the present invention. This graph represents a temperature reading measured at an O-ring 56 located adjacent to the barrier material 64 and spaced from the processing region 18. In the test, six consecutive epitaxial silicon deposition processes were performed up to about 2600 times, followed by an extended cleaning of 1200 ° C., HCl for about 26 hours.
This includes operations performed between 00 and 4600 times or for about 33 minutes. Immediately after this extended HCl cleaning, six additional epitaxial silicon deposition cycles were performed. As shown by the graph, the O-ring used with the barrier material of the present invention was exposed to a maximum temperature of about 235 ° C. after an extended 1200 ° C. cleaning.

FIGS. 12 and 13 show the resistivity of an intrinsic epitaxial silicon film deposited in a reactor 15 having the barrier of the present invention installed as described with respect to FIG. In each of the tests illustrated in FIGS. 12 and 13, three wafers were processed sequentially, with each wafer receiving at least 10 μm of epitaxial silicon deposition in each process. Measurements of resistivity or cleanliness are provided in Ω-cm as a function of film thickness (μm). The resistivity of the surface of the deposited epitaxial film is 0
Indicated by μm depth measurement. Due to aspects related to resistivity measurement techniques, the actual resistivity measurement at the surface of the measurement film may be lower. Recognizing the effects of these surface effects, the resistivity is commonly referred to as "exceeding" the accurately measured surface resistivity.

FIG. 12 represents the resistivity measurements of three consecutive epitaxial silicon deposition sequences where at least 10 μm of epitaxial silicon was deposited on each substrate. The three substrates processed and measured in FIG. 12 were processed before performing the stress test described above with respect to FIG. The lowest resistivity or lowest clean epitaxial film was deposited during the third sequence and the resulting film had a resistivity greater than 550 Ω-cm. Very good quality silicon was deposited in the first and second deposition sequences, where resistivity greater than 5000 ohm-cm and resistivity greater than 7500 ohm-cm were measured.

FIG. 13 shows three successive 10 μm steps performed after performing the stress test illustrated in FIG. 11 and described above.
4 illustrates a resistivity measurement for a deposition sequence. FIG.
The lowest resistivity or lowest cleanness silicon, as illustrated in Example 1, is greater than about 450 Ω-cm and was deposited during the first deposition sequence performed after the stress test. The resistivity of the second deposited film and the resistivity of the third deposited film were 1300 Ω-cm or more and 6500 Ω-cm or more, respectively.

As shown by the results illustrated in FIGS. 11, 12 and 13, processing reactors using a barrier material according to the present invention can extend the life of the primary O-ring seal because The material provides the insulation benefits to the O-ring, as the barrier material helps to keep the O-ring temperature below 250 ° C. even during the most demanding 1200 ° C. HCl cleaning cycle. Even if O-ring deterioration occurs, the cleanness of the film deposited in the processing region 18 remains high.
The resistivity measured after the stress test indicates that the barrier material prevented contaminants from reaching the processing area 18. Proof of the anti-contamination quality of the barriers of the present invention is provided by FIG. 13 and is obtained from films deposited in reactors having barriers of the present invention after the reactors have undergone the stress test described above with respect to FIG. Provided by electrical resistivity measurements.

Typically, the process film resistivity requirements (as measured in FIGS. 12 and 13) are typically about 5 to 10 times the design resistivity requirements for a given application. Therefore,
Devices or applications that require a resistivity of about 10-20 Ω-cm will require a process film resistivity measurement of about 50-200 Ω-cm. Even after performing the stress test, the reactor 15 having the barrier of the present invention has a resistance of 400 Ω.
High-purity epitaxial films were deposited with resistivity greater than -cm.

The above-described processing reactor 15 having the barrier of the present invention can accommodate a number of different processes. The advantages of the present invention are better understood by way of illustration in terms of epitaxial silicon deposition and cleaning sequence. 1 for both deposition and cleaning operations
Temperatures above 000 ° C, more usually about 1100-120
The epitaxial silicon processing operation is particularly difficult because it is performed at a temperature of 0 ° C. The cleaning sequence is 1
In some cases, process steps as high as 225 ° C may be employed. Thus, the deposition of epitaxial silicon poses particular problems because the deposition and cleaning cycles made create the demands of continued high temperature operation for the epitaxial processing equipment.

In a typical epitaxial silicon chemical vapor deposition cycle, a substrate 20 is placed on a susceptor 22 in a double dome reactor 15 having an inert barrier according to the present invention. After placing the substrate on the susceptor 22, the susceptor 22, substrate 20 and preheat ring 24 are heated by a plurality of high intensity lamps 26 to a reasonable deposition temperature. A typical epitaxial silicon deposition process is between about 950 ° C. and 12 ° C. depending on the source gas used.
Performed at 50 ° C. For example, the deposition temperature of silicon tetrachloride (SiCl4) is about 1150-1250C, while the deposition temperature of silane (SiH4) is about 950-1050C. The drive 23 can rotate to provide a time-averaging environment to the cylindrically symmetrical substrate 20. Deposition gas is introduced into processing region 18 from an external source via supply line 30 and chamber inlet 32. The gas mixture typically has a source of silicon, such as, but not limited to, silane, disilane, dichlorosilane, trichlorosilane, silicon tetrachloride, and the like. A non-reactive carrier gas, such as hydrogen, is injected into the processing chamber along with the reactant gases.

The deposition gas flows from the inlet 32 to the exhaust port 36, the preheating ring 24, the susceptor 22, the substrate 20, and the like, and then to the exhaust system. Substrate 20
Although intended only for deposition on top, deposition also occurs on other chamber surfaces that are hot enough to cause a deposition reaction. For example, deposition can occur on surfaces such as the preheating ring 24, the end, top, and bottom domes 12 and 16 of the susceptor 22 that are not covered by the substrate 20, and depending on the design of the reactor, such as the backside of the susceptor 22 and the preheating ring 24. Occurs. During the deposition cycle, the barrier 64 prevents heated deposition reactants in the processing region 18 entering the gap between the liner 118 and the top dome 12 from reaching the O-ring 56. Similarly, barriers 66 prevent heat deposition reactants in the processing region 18 from entering the gap between the liner 118 and the bottom dome 16 from reaching the O-ring 58.
Prevent. Barriers 62, 64, 66 and 68 provide thermal isolation from the high temperatures present in processing region 18 during epitaxial silicon deposition.

Further, because the barriers 64 and 66 are advantageously located between each O-ring and the processing area 18, particles or other contaminants generated by each O-ring enter the processing area 18 and fall on the substrate 20. Contamination of the deposited film is prevented. Similarly, the barrier 62 includes O-rings 50 and 5
2 to prevent the possibility that contaminants or particles generated by the reactor 2 may reach or coat the processing area 18 or from the lamp 26 at the top of the reactor 15 to the processing area 18.
To prevent adverse effects on the transfer of radiant energy to the Similarly, the barrier 68 may prevent contaminants or particles generated by the O-ring 60 from reaching or coating the processing area 18 or radiating the lamp 26 from the bottom portion of the reactor 15 to the processing area 18. Prevents adverse effects on energy transfer.

The deposition cycle is repeated for each substrate to be processed. In a typical epitaxial deposition sequence, a number of substrates are processed, and then a cleaning sequence is performed once inside the processing area 18 to remove deposits that have accumulated during the deposition cycle. Commercially realistic deposition and cleaning sequences are particularly contemplated, wherein a step of depositing about 20 μm of epitaxial silicon is followed by a long, HCl-based cleaning cycle lasting about 5-10 minutes once. . After the last substrate in the deposition sequence has been processed and removed from the processing area, the temperature of the processing area 18 (measured at the susceptor 22) is increased to about 1200 ° C. Next, HCl is introduced into the processing region 18 via the inlet 32. HCl in the gas phase
Dissociates within the processing region 18 and reacts with silicon deposits and other deposits to form volatile by-products. Thereafter, these volatile by-products are exhausted from the processing region 18 through the exhaust port 36.

As in the case of the deposition process, the barrier 64
And 66 are seal O-rings 56 due to degradation due to direct contact with the hot gases used during the cleaning process.
And 58 are protected. Particularly with respect to the cleaning process, barriers 64 and 66 prevent chemical erosion caused by contact between O-rings 56 and 58 and reactive cleaning agents used in processing area 18 during a cleaning cycle. 120 typical for epitaxial reactors
For 0 ° C. HCl cleaning, chlorine is one of the highly reactive cleaning agents used.

During the cleaning cycle, the liner 118
Treatment area 1 entering the gap between the dome 12 and the top dome 12
The barrier 64 prevents the heated cleaning gas in 8 from reaching the O-ring 56.

Similarly, the barrier 66 prevents the heated cleaning gas in the processing region 18 from entering the gap between the liner 118 and the bottom dome 16 from reaching the O-ring 58.
Prevent. Also, barriers 62, 64, 66 and 68
Provides thermal insulation from the high HCl cleaning temperatures used in the processing region 18. Further, barriers 64 and 6
6 is advantageously positioned between the O-ring and the processing region 18 to prevent particles or other contaminants generated by the O-ring from entering the processing region 18 and interfering with the cleaning process. If the O-rings 50 and 52 deteriorate to produce particles or contaminants, the barrier 62
Prevents the particles or contaminants from reaching or coating the processing area 18 or adversely affecting the transfer of radiant energy from the lamp 26 to the processing area 18 at the top of the reactor 15. To prevent If the O-rings 60 are degraded to produce particles or contaminants, the barrier 68 will
It prevents the possibility of reaching or coating the processing area 18 or adversely affecting the transfer of radiant energy from the lamp 26 to the processing area 18 at the bottom portion of the reactor 15.

Although described above with respect to epitaxial silicon deposition, other processing operations can advantageously utilize the barrier layer of the present invention. For example, the deposition process of amorphous silicon, doped silicon or polysilicon employs the same 1200 ° C. HCl cleaning cycle as described above. These types of deposition reactors can also use the barriers of the present invention to achieve the ability to perform long 1200 ° C. HCl cleaning cycles without O-ring degradation. Just as the barriers of the present invention prevent chemical attack to chloride, the barrier is used with other cleaning chemistries to prevent other types of chemical attack as well. For example, the barrier of the present invention comprises NF3
In these processing chambers that use fluorine-based cleaning chemistries, such as with, can be used to prevent chemical attack by fluorine.

While particular embodiments of the present invention have been shown and described, further modifications and improvements will occur to those skilled in the art. Therefore, it is desired to understand that the invention is not limited to the specific forms shown herein, and the claims are intended to cover all modifications that do not depart from the essence and scope of the invention. Is done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a prior art CVD processing reactor.

FIG. 2 is a cross-sectional view of a sidewall of a prior art CVD reactor.

FIG. 3 is a cross-sectional view of a sidewall of a CVD processing reactor according to the present invention.

FIG. 4 is a perspective view of an inert barrier according to the present invention.

FIG. 5 is a top view of the inert barrier of the present invention.

FIG. 6 is an AA cross-sectional view of the inert barrier of FIG. 5;

FIG. 7 is an initial enlarged view B of the overlap region of the inert barrier according to the present invention.

FIG. 8 is a final enlarged view B of the overlap region of the inert barrier according to the present invention.

FIG. 9 is a cross-sectional view of the side wall in an unloaded position.

FIG. 10 is a cross-sectional view of a side wall at a loading or installation position.

FIG. 11 is a graph illustrating the temperature of an O-ring as a function of time for an O-ring placed in a chamber having a barrier layer in accordance with the present invention.

FIG. 12 is a graph of film thickness versus resistivity for a series of wafers processed in a reactor having an inert barrier according to the present invention.

FIG. 13 is a graph of film thickness versus resistivity for a series of wafers processed in a reactor having an inert barrier according to the present invention.

[Explanation of symbols]

12 Top dome, 40 Upper clamp ring, 44
Base ring, 50, 52, 54, 56 ... O-ring.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Romaine Bude Rominy United States, California, Menlo Park, Monte Rosa Drive 675, Number 813 (72) Inventor David Cay Carlson United States of America, California, Santa Clara, Dundee Drive 3408

Claims (17)

[Claims] 1. A semiconductor substrate processing apparatus, comprising: (a) a processing chamber having a first member, a second member, and a processing region; and (b) a pressure-controlled environment in the processing region. A vacuum tight seal between the first member and the second member, and (c) separating the seal from the processing region;
And a barrier disposed between the second member and the second member and substantially non-reactive with respect to a process performed in the processing region. 2. The apparatus of claim 1, wherein said barrier is substantially non-reactive with an epitaxial silicon deposition process performed in said processing region. 3. The method according to claim 1, wherein the barrier has a thickness of about 12 in the processing area.
The apparatus of claim 1, wherein the apparatus is substantially non-reactive for processes having a temperature of 00C. 4. The method according to claim 1, wherein the barrier comprises about 12
The apparatus of claim 1, wherein the apparatus is substantially non-reactive in processes having HCl at a temperature of 00C. 5. The device of claim 1, wherein said inert barrier comprises an expanded tetrafluoroethylene resin. 6. The barrier of claim 1, wherein the barrier is sufficiently thick so that when shrinkage occurs in the thickness of the barrier, the barrier fills an allotted gap between the first member and the second member. An apparatus according to claim 1. 7. The apparatus according to claim 1, wherein the barrier is a continuum and circumscribes the processing area. 8. The barrier comprising a slidably coupled end, a first length at a first temperature, and a second length at a second temperature, wherein the first temperature is Lower than the second temperature, the second length is less than the first length, and the barrier is slidably coupled to the end while the barrier continues to separate the seal from the processing area; The apparatus of claim 7, wherein the barrier allows the barrier to contract from the first length to the second length. 9. The seal, after the barrier has contracted from the first length to the second length, leaves the area separated from the process by about half the thickness of the barrier. An apparatus according to claim 8. 10. An apparatus for depositing silicon, comprising: (a) a processing chamber having a first element, a second element, and a processing area; and (b) a pressure control in the processing area. An O-ring between the first element and the second element to enable the process to be performed; and (c) a linear shaped material comprising expanded tetrafluoroethylene resin, wherein the material comprises the processing region Substantially inert to the temperature, pressure and chemical environment within the material;
A first notched end, a second notched end compliantly coupled to the first notched end, a thickness and a length, wherein the linear material comprises the first notched end; Circumscribing the processing region when the notched end of the second notched end is joined to the second notched end, such that the inert material separates the processing region from the O-ring, Equipment to be equipped. 11. The process area is separated from the O-ring by about half the thickness of the inert material,
11. The apparatus of claim 10, wherein the first notched end is on the same line as the second notched end. 12. The first notched end and the second notched end.
11. The apparatus of claim 10, wherein the length of the material is long enough such that the notched ends of the material overlap within the processing area regardless of temperature and material shrinkage. 13. An improved silicon deposition apparatus, comprising: (a) a processing chamber having a first element, a second element, and a processing area suitable for deposition of intrinsic silicon; b) a pressure seal formed between the first and second elements to provide a pressure controlled environment within the processing region; and (c) the first seal separating the pressure seal from the processing region.
A barrier layer formed between the second element and the second element, the barrier layer preventing contaminants from the seal from reaching the processing area, and the barrier is disposed within the processing area. An apparatus that provides insulation for the seal from heat and chemicals used, and wherein the barrier is substantially inert to heat and chemicals used in the processing area. 14. A semiconductor substrate processing apparatus, comprising: (a) a top dome, a bottom dome, a base ring, a clamp ring coupled to and separating the top dome and the bottom dome, and A processing chamber comprising a susceptor disposed within a processing area defined by the bottom dome, the base ring, and the clamp ring; a plurality of lamps illuminating the susceptor; and a quartz liner disposed adjacent to the susceptor. (B) a seal disposed between the base and each dome and a seal between the clamp ring and each dome, wherein the dome, the base ring, and the clamp ring are compressible with each seal. Each of said seals, contacting the seal to enable a pressure controlled environment within the processing region;
(c) a barrier disposed between the seal and each of the processing regions, the barrier preventing contaminants from the seal from reaching the processing region, wherein the seal and the barrier are Disposed in a groove formed in the clamp ring and the base ring;
An apparatus comprising the barrier. 15. The apparatus according to claim 14, wherein said base ring and said clamp ring are formed of stainless steel. 16. The apparatus of claim 14, wherein said seal has a circular cross section and said barrier has a square cross section. 17. The apparatus of claim 14, wherein the thickness of the barrier is less than twice the depth of the groove.